Image recording device with optical switch panel over photsensitive body

ABSTRACT

An image recording device has an optical switch panel disposed nearly or directly in contact with a photosensitive body. The optical switch panel contains many liquid crystal display dot elements between a pair of boundary layers and serves to form on the photosensitive body an image which is displayed on the optical switch panel. The boundary layer on the side of the photosensitive body is significantly thinner than that distal therefrom.

This is a divisional of application Ser. No. 225,628 filed July 27, 1988now U.S. Pat. No. 4,855,818, which is a continuation of application Ser.No. 120,699 filed Nov. 10, 1987, now abandoned which is a continuationof application Ser. No. 943,815 filed Dec. 29, 1986, now abandoned,which is a continuation of application Ser. No. 748,487 filed June 25,1985 , now abandoned.

This invention relates to a recording device with a liquid crystaloptical switch panel made of a plurality of liquid crystal display dotelements so that a display image on the panel can be formed and recordedon a photosensitive film or paper such as OPC (organic photoconductor).

A conventional color scanner, as shown in FIG. 3, uses a whitefluorescent lamp 1 to scan a document 3 on a table 2 which moves in thedirection of arrow 9. The reflected light is lead to a disk-shaped RGBcolor filter 5 by means of mirrors 4-1 and 4-2 and the transmitted lightis focused by a lens 6 so that an optical image of the document 3 willbe formed on a CCD sensor 7. The RGB color filter 5 is divided intothree filter areas which are red (R), green (G) and blue (B) and itscenter is directly connected to the axis of rotation of a motor 8 whichrotates in synchronism with the scanning of the CCD sensor. In short,the reflected light from the document is decomposed into colorcomponents by the rotation of the RGB color filter 5 and they aredetected by the CCD sensor 7 and outputted, for example, as a 3-bitcolor information.

Since the RGB color filter 5 is so positioned in the conventionalapparatus described above that only a portion of it is on the opticalpath of the deflected light from the document 2, while a large portionof it sticks out of the optical path, the apparatus as a wholeinevitably becomes large. As for the white fluorescent lamp 1 used inthis apparatus, variations in its luminance due to the ambienttemperature are known to be great. For example, its luminance at 30° C.is about one-half of that at 0° C. For this reason, a laminate heater iscommonly installed around a fluorescent lamp, the temperature of thelaminate heater being detected by a thermostat or the like so that thewall temperature of the fluorescent lamp will be maintained at 30°-40°C. Power of 50-70W is typically consumed by such a laminate heater.

It is therefore an object of this invention in view of the above toprovide a document reading apparatus with a color filter formed in acylindrical shape, having a light source inside this cylinder so thatthe apparatus can be made smaller and its power consumption can bereduced.

In order to explain another aspect of the present invention, there isshown in FIG. 6 a conventional recording apparatus for recording onpaper an image displayed on a liquid crystal optical switch panel. Alamp 22 is provided behind a liquid crystal optical switch panel 21 madeof liquid crystal display dot elements and the light beam from the lamp22 passing through the panel 21 is lead to a photosensitive body 25 bymeans of a lens 23 and a mirror 24 in such a way that the display on theliquid crystal optical switch panel 21 will be focused by the lens 23.Numeral 27 is a charging means and a latent image is formed on thephotosensitive body 25 while it moves in the direction of arrow 26 insynchronism with the operation of the liquid crystal display dotelements. The latent image formed here is made visible in a developingmeans 28 and this visible image is copied by a copier 31 on a recordingsheet which is sent in from a cassette 29 by a roller 30 in synchronismwith the motion of the photosensitive body 25. The recording sheet issubsequently sent to a fixer 32 where the visible image is fixed, andthen is taken out of the device.

There have been various attempts to improve the recording quality of adevice of this type in view of the low sensitivity of the body 25. Verybright light sources such as halogen lamps have been tried and theopening angle of the lens 23 has been enlarged to improve its opticalefficiency. If a bright light source is used, however, the heatgenerated by it raises the ambient temperature and deteriorates thecharacteristics of the liquid crystal optical switch panel and thephotosensitive material. If the lens opening is made larger, on theother hand, the cos ⁴ θ rule comes into play and there arise problems ofoperation as well as adjustment of the optical system because the focaldepth becomes reduced. The cost of the lens will also increase in thissituation.

It is therefore another object of this invention in view of the above toprovide a recording device in which a liquid crystal optical switchpanel is installed differently so that the recording quality can beimproved even with a material with low photosensitivity and further thatthe optical system can be simplified, the device can be made smaller andits manufacturing cost can be reduced.

FIG. 1 is a schematic showing the structure of a document readingapparatus according to one embodiment of the present invention.

FIG. 2 is a schematic showing the structure of another document readingapparatus according to the present invention.

FIG. 3 is a schematic showing the structure of a conventional documentreading apparatus.

FIG. 4 is a schematic showing the structure of a recording deviceembodying the present invention.

FIG. 5 is an enlarged view of a portion of the device of FIG. 4.

FIG. 6 is a schematic showing the structure of a conventional recordingdevice.

In FIG. 1, which is a schematic showing the structure of a documentreading apparatus according to one embodiment of the present invention,numeral 1 is a white fluorescent lamp with an aperature, having areflective layer on a portion of its tube. A laminate heater 10 isprovided on its tube wall. A heater control circuit is provided to thislaminate heater so that the wall temperature will be always maintainedat about 40° C. Numeral 3 indicates a document adapted to beautomatically moved in the direction of arrow 12 in synchronism with thelight scanning. A phototransmissive film document is used here inparticular. Numeral 5 is a cylindrically formed RGB color filter withits sidewall equally divided in the axial direction into three RGBfilter areas. The white fluorescent light 1 is contained inside thiscylindrical filter 5 as shown. On the periphery of the filter 5 at oneof its ends, there is provided a gear 11 which engages with another gearon the rotary axis of a motor 8 so that only the main filter body iscontrollably rotated by 120° in synchronism with the scanning of a CCDsensor 7. Numeral 6 is a lens for collecting the transmitted light fromthe document to form an optical image of the document on the CCD sensor7.

In summary, light from the white fluorescent lamp 1 of this documentreading apparatus thermally controlled by the laminate heater 10illuminates the document 3 through a cylindrical color filter 5 and thetransmitted beam is focused by the lens 6 to form an image on the CCDsensor 7. The cylindrical color filter 5 is rotated by 120° each time sothat three light sources for R, G and B are formed and the beams fromthese sources are made incident on the same portion of the document 3 sothat its color information can be read out.

Since the white fluorescent lamp 1 is contained inside the RGB colorfilter 5 formed in a cylindrical shape, the light source and the filtercan be constructed as a single unit and the apparatus can thus be madeextremely compact. Moreover, since the white fluorescent lamp 1 issurrounded by the cylindrical color filter 5, the heat generated by thelaminate heater 10 is not diffused away easily. Accordingly, powerconsumption by the laminate heater 10 can be significantly reduced.

Another embodiment of the present invention is illustrated in FIG. 2wherein components similar to those in FIG. 1 are indicated by the samenumerals.

This embodiment is characterized in that the cylindrical color filter 5contains therein not only the white fluorescent lamp 1, but also acylindrical plano-convex lens 13 for linearly focusing the light fromthe lamp 1 and that only the color filter 5 will rotate around them sothat color correction can be effected inclusive of the optical systemsuch as the cylindrical lens 13. This embodiment is adapted to focus adisplay on a liquid crystal switch panel 14 made of a plurality of dotelements through a lens 6 on a photosensitive film 15 for recording.

In summary, a document reading apparatus of this invention has acylindrical color filter containing a light source inside so that theapparatus can be made compact, the luminence of the source can be stablymaintained and the power consumption can be reduced.

FIG. 4 shows the structure of a recording device according to thepresent invention. Components shown therein which are similar to thosein FIG. 6 are indicated by like numerals. Thus, numeral 21' is a liquidcrystal optical switch panel, numeral 22 is a fluorescent lamp with anaperature, numeral 25 is a photosensitive body, numeral 27 is a chargingmeans, numeral 28 is a developer by means of which a latent image on thephotosensitive body 25 is made visible or a visible image (such as atoner image) is obtained, numeral 29 is a cassette for containingrecording paper, numeral 30 is a roller for feeding recording paper fromthe cassette 29 in synchronism with the motion of the photosensitivebody 25, numeral 31 is a copier for copying the visible image on thephotosensitive body 25 onto the recording paper, numeral 32 is a fixerfor fixing the image copied on the recording paper, numeral 33 is acylindrical plano-convex lens, and numeral 34 is a driving drum formoving the photosensitive body 25. The liquid crystal optical switchpanel 21' has thin display surfaces which are parallel to the axialdirection of the drum 34, each with a width of about 0.1mm correspondingto one or several lines (the line length being nearly equal to thetransverse width of the photosensitive body 25) and can be driven foreach dot by a display driving circuit. In other words, it is sostructured that each dot can be operated as a small optical shutter.

From the point of view of basic construction, the liquid crystal opticalswitch panel 21' of this invention is no different from the conventionalpanel, having liquid crystal sealed between glass substrates 35 and 36and being provided with polarization plates 37 and 38 as shown in FIG.5. As will be explained immediately below, however, the liquid crystaloptical switch panel 21' of this invention is substantially differentfrom the conventional type.

Firstly, the total thickness of the glass substrate 36 and thepolarization plate 38 on the side facing the photosensitive body 25 ismade extremely small (0.2 mm or less) while it was conventionally about1.3 mm or more. This prevents the image from broadening on thephotosensitive body 25 even if the angle of incidence 8 becomes large sothat high-quality recording can be effected.

Secondly, there is a spacer 39 inserted, as shown in FIG. 5, at aposition other than the space corresponding to one or more lines where aliquid crystal is sealed in. This prevents deformation of this space byan external force when the panel comes into direct contact with thephotosensitive body 25 on the drum 34. The total thickness of the glasssubstrate 35 and the polarization plate 37 on the side facing thecylindrical lens 33, however, is about the same as the conventionalvalue (about 2-3 mm) so as to give a sufficient strength to thestructure.

The liquid crystal optical switch panel 21' thus constructed is disposednear or in direct contact with the photosensitive body 25 on the drum 34so that the light from the fluorescent lamp 22 which has been focusedinto a single line by the cylindrical lens 33 thereabove will illuminatethe display surface of the switch panel 21'. Accordingly, a latent imageof an entire display can be formed on the photosensitive body 25 byrotating the drum 34 in the direction of the arrow 26 in synchronismwith the timing of image display corresponding to one line or severallines on the display surface of the liquid crystal optical switch panel21'. This latent image is made visible as a toner image by the developer28, copied on recording paper by the copier 31 and fixed by the fixer32.

In summary, the present invention teaches the improved liquid crystaloptical switch panel 21'to be placed near or in direct contact with aphotosensitive material for recording. Since the distance between thelight source 22 and the photosensitive body 25 has been made muchshorter, a light source which is no brighter than a fluorescent lamp canbe used with a photosensitive body 25 of low sensitivity for recording.Moreover, the liquid crystal optical switch panel 21'is thin on the sideof the photosensitive body 25 but no deformation will result from apressure on its body because although the part containing liquid crystalis only about 279 0.1 mm in thickness, the panel is additionallyprotected by the spacer 39. Thus, recording of very high quality can beeffected by a device of the present invention. Furthermore, since theoptical system can be simplified and made smaller as shown in FIGS. 4and 6, the manufacturing cost of the device can be significantlyreduced.

Although only one example of recording device using the electronicphotography process and a photosensitive body such as organicphotoconductor has been shown above, the present invention can beequally applicable to a recording device depending on the conventionalphotographic process and a photosensitive film or paper. If a liquidcrystal optical switch panel 21' of a flexible type is used,furthermore, it can be matched to the curvature of the photosensitivebody 25 caused by the drum 34 and its durability can be improved.

What is claimed is:
 1. An image recording device comprisingaphotosensitive member, and an optical system which includes a liquidcrystal optical switch panel with a plurality of liquid crystal displaydot elements between a first boundary layer and a second boundary layer,and serves to form on said photosensitive member an image displayed onsaid liquid crystal optical switch panel, said first boundary layerbeing disposed nearly or directly in contact with said photosensitivemember and significantly thinner than said second boundary layer whichis separated from said photosensitive member.
 2. The recording device ofclaim 1 wherein said plurality of liquid crystal display dot elementsform at least one thin display surface for displaying one or more linesof an image.
 3. The recording device of claim 2 wherein said liquidcrystal optical switch panel has a spacer disposed outside said at leastone thin display surface formed by said plurality of liquid crystaldisplay dot elements.
 4. The recording device of claim 1 wherein saidliquid crystal optical switch panel has flexible substrates.
 5. Therecording device of claim 2 wherein each said at least one thin displaysurface has a width of about 0.1 mm.
 6. The recording device of claim 2wherein liquid crystal is sealed in said liquid crystal display dotelements.
 7. The recording device of claim 3 wherein liquid crystal issealed in said liquid crystal display dot elements.
 8. The recordingdevice of claim 1 wherein both said first and second boundary layerinclude a glass substrate and a polarization plate.
 9. The recordingdevice of claim 1 wherein said second boundary layer is about 2-3 mm inthickness.
 10. The recording device of claim 1 wherein said firstboundary layer is 0.2 mm or less in thickness.
 11. The recording deviceof claim 1 wherein said second boundary layer is about 2-3 mm inthickness.